JPS62149736A - Production of porous film or sheet - Google Patents

Abstract

PURPOSE:To obtain a porous film or sheet excellent in flexibility, tear strength, gas permeability and moisture permeability, by stretching a film or sheet comprising a specified ethylene/alpha-olefin copolymer and a filler at a specified temperature. CONSTITUTION:A composition comprising 10-80wt% ethylene/alpha-olefin copolymer having a density of 0.860-0.910g/cm<3>, a boiling n-hexane-insoluble portion >=10wt% and a maximum peak temperature in differential scanning calorimetry >=100 deg.C and 20-90wt% filler is molded into a film or a sheet. This film or sheet is stretched at a temperature by at least 10 deg.C lower than the maximum peak temperature of the ethylene/alpha-olefin copolymer in differential scanning calorimetry. Examples of the filler which can be suitably used include calcium carbonate, talc, silica, barium sulfate, aluminum hydroxide and magnesium hydroxide.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a porous film or sheet (hereinafter both are collectively referred to as a film).

More specifically, it is highly flexible, has strong tear strength, and has excellent breathability and moisture permeability, and is suitable for clothing, sanitary products, medical supplies,
This invention relates to a method for producing porous films that can be used in fields such as filter media.

[Prior art]

BACKGROUND ART It has been conventionally practiced to produce a porous film by blending a filler with a polyolefin resin such as polyethylene, melt-molding the resulting film, and then stretching the film. However, if a polyolefin resin containing a filler is simply used, it has poor stretching properties and cannot be stretched at a low stretching ratio.On the other hand, when stretched at a high stretching ratio, tear strength decreases and there are problems such as poor flexibility. was. Therefore, various attempts have been made to overcome these problems. Most of these methods involve adding liquid compounds in addition to the polyolefin resin and filler. For example, in JP-A-57-47334, liquid polybutadiene and liquid polybutene were used in JP-A-57-203520.
Then, liquid polyhydroxy saturated hydrocarbon was prepared in JP-A-58
In JP-A-149925, liquid polyimprene rubber was added, and in JP-A-59-140235, epoxidized vegetable oil was added. However, when porous films obtained by these methods come into contact with solvents or chemicals, liquid additives are eluted, which poses a problem. In addition, even the most flexible polyolefin among these polyolefins has a density of 0.910 to 0.
940'i-/Cr/l (D linear low-density carbon) processing f7, the flexibility is still insufficient and there is a need for a film with even more flexibility.

[Problem that the invention seeks to solve]

Method for producing a porous film based on polyolefin resin gold In view of the above-mentioned current situation, we have developed a method for producing a porous film that can be stretched at a low magnification in order to obtain a film with excellent longitudinal and horizontal balance in tear strength and other physical properties. The present invention was completed as a result of intensive research into a method for obtaining a film with excellent flexibility, air permeability, moisture permeability, solvent resistance, and chemical resistance.

[Means for solving the problem] The present invention has a density of 0.8609-/l or more, 0.910
PΔ, the boiling n-hexane insoluble matter (hereinafter referred to as "C6 insoluble matter") is 10% by weight or more, and the maximum peak temperature (hereinafter referred to as "TmJ") shown by differential scanning calorimetry (DSC) is 100 ° C. A film obtained by melt-molding a composition consisting of the above-mentioned ethylene-α-olefin copolymer (hereinafter referred to as "ULDPEJ") of 10 to 80 weight percent and a filler of 20 to 90 weight percent is formed by melt-molding the ethylene copolymer. Tm of
This is a method for producing a film characterized by stretching at a temperature lower than 19103°C.

The ULDPE used in the present invention contains ethylene and 3 to 1 carbon atoms.
It is a copolymer of No. 2 with α-olefin.

Specific examples of the α-olefin include propylene, butene-1,4-methylbenzone-1, hexe/-1, octene-1, decene-1, and dodecey-1. α in ethylene-α-olefin copolymer
- The content of olefins is between 2 and 40 mol, preferably 5
~20 moles.

The method for producing ULDPE (c) used in the present invention will be explained below.

First, the catalyst system used is a combination of a solid catalyst component containing magnesium and titanium and an organic aluminum compound. Examples of solid catalyst components include magnesium metal, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium chloride, etc., or double salts and double oxides containing a metal selected from silicon, aluminum, and calcium and magnesium atoms. compounds, carbonates, chlorides or hydroxides, as well as these inorganic solid compounds? Titanium compounds are supported by known methods on inorganic sulfur compounds containing magnesium, such as those treated with or reacted with oxygen-containing compounds, sulfur-containing compounds, aromatic hydrocarbons, and substances containing nitrogen. There is.

The oxygen-containing compounds mentioned above include, for example, organic oxygen-containing compounds such as water, alcohol, phenol, ketone, aldehyde, carboxylic acid, ester, polysiloxane, acid amide, etc., and inorganic oxygen-containing compounds such as all alkoxides and metal oxychlorides. These include oxygen-containing compounds. Examples of sulfur-containing compounds include organic sulfur-containing compounds such as thiol and thioether, and inorganic sulfur compounds such as sulfur dioxide, sulfur trioxide, and sulfuric acid. Aromatic hydrocarbons include various monocyclic and polycyclic aromatic hydrocarbon compounds such as benzene, toluene/xylene, anthracene, and phenanthrene. Examples of I.logen-containing substances include compounds such as chlorine, hydrogen chloride, metal chlorides, and organic logenides.

Examples include titanium compounds, halides, alkoxy halides, alkoxides, and oxides of titanium. As the titanium compound, a tetravalent titanium compound and a trivalent titanium compound are suitable, and the tetravalent titanium compound is specifically represented by the general formula 'l't (OR
)nXi-n is preferred. Here, R represents an alkyl group, aryl group, or aralkyl group having 1 to 20 carbon atoms, X represents a nitrogen atom, and n represents 0≦n≦
It is 4. For example, titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, monomethoxytrichlorotitanium, jetoxydichlorotitanium, trimethoxymonochlorotitanium, tetramethquine titanium, monoethoxytrichlorotitanium,
Jetoxydichlorotitanium, triethoxymonochlorotitanium, tetramethquine titanium, monoinpropoquine trichlorotitanium, diisopropoquine dichlorotitanium, triinpropoxymonochlorotitanium, tetrainpropoxytitanium, monobutoxytrichlorotitanium, jetoxydichlorotitanium, monopen Examples include toxitrichlorotitanium, monophenoquine trichlorotitanium, diphenoxydichlorotitanium, triphenoxymonochlorotitanium, and tetraphenoquine titanium.

As trivalent titanium compounds, titanium tetrahalides such as titanium tetrachloride and titanium tetrabromide can be combined with hydrogen, aluminum,
Examples include titanium trinologenide, which is obtained by reducing titanium or an organometallic compound of a metal from group Ⅰ to group 1f of the periodic table. Also, the general formula T i (OR) mx
, -m (R is an alkyl group, aryl group or aralkyl group having 1 to 20 carbon atoms, X is a halogen atom,
Examples include trivalent titanium compounds obtained by reducing a tetravalent alkoxy titanium halide represented by O<m<4) with an organometallic compound of a metal from Group 1 to Group 1 of the periodic table.

Among these titanium compounds, tetravalent titanium compounds are particularly preferred.

Examples of other catalyst systems include a catalyst system in which a reaction product of an organomagnesium compound such as a so-called Grignard reagent and a titanium compound is used as a solid catalyst component, and an organoaluminum compound is combined therewith. Examples of organomagnesium compounds include organomagnesium compounds with the general formula RMgX, R, Mg, RMg(OR) (R is an organic residue having 1 to 20 carbon atoms, X is a halogen atom), and ether complexes thereof; Furthermore, these organic magnonium compounds are modified by adding other organic metal compounds such as organic sodium, organic lithium, organic potassium, organic boron, organic calcium 7, organic zinc, etc. be able to.

In addition, as an example of another catalyst system, as a solid catalyst component, 5
i02, A1. An example is a solid material obtained by contacting an inorganic oxide such as O, with the above-mentioned solid catalyst component containing at least magnesium and titanium, which is combined with an organoaluminum compound. In addition to 5i02 and A1tOi, examples of inorganic oxides include Cao, Bzos, and 5n02, and double oxides of these oxides can also be used without any problem.

Specific examples of organoaluminum compounds to be combined with the above solid catalyst component include general formulas R3Al, R,A
IX, RAIX2, R2AlOR, RAI(OR) (different compounds may be used) are preferable;
triethylaluminum, triimbutylaluminum, trihexylaluminum, trioctylaluminum, diethylaluminum chloride, diethylaluminum ethoxide, ethylaluminum sesquichloride,
and mixtures thereof.

The amount of the organoaluminum compound to be used is not particularly limited, but it can be used in a total amount of 0.1 to 1000 times the amount of the titanium compound.

The copolymerization reaction is carried out in the same manner as an ordinary olefin polymerization reaction using a Ziegler type catalyst. That is, all reactions are carried out substantially in the absence of oxygen, water, etc., in a gas phase or in the presence of an inert solvent, or using the monomer itself as a solvent.

The conditions for copolymerization of ethylene and α-olefin are that the temperature is 20 to 300°C, preferably 40 to 200°C, and the pressure is normal pressure to 70 kg/crIt-G, preferably 2 kp/m-G to 60 kf. /crIt-G.

Although the molecular weight can be controlled to some extent by changing conditions such as the copolymerization temperature and the molar ratio of the catalyst, it can be effectively controlled by adding hydrogen to the polymerization system. Of course, a two-step or more multi-step polymerization reaction with different polymerization conditions such as hydrogen concentration and polymerization temperature can also be carried out without any problems.

The ULDPE used in the present invention has a density of 0.860
P/(M1 or more, less than 0.910 f10yr1, C6
The insoluble matter is present at a weight ratio of 10 or more and a Tm of 100°C or more. If a film with a density of less than 0.8607 weight m is used, the heat resistance and strength of the film will be insufficient, and if a film with a density of 0.910 P/l:i or more is used, not only will the flexibility of the film be low, but it will also be difficult to stretch. inferior in gender, 2
At a low stretching ratio of ~4 times, stretching unevenness (stretched portions and unstretched portions coexist) occurs.

If the C6 insoluble content is less than 10% by weight and the Tm is less than 100°C, the heat resistance and strength of the film will be insufficient.

The method for measuring C1 insoluble content and Tm in the present invention is as follows.

[Measurement method of C6 insoluble content] Using a hot press, form a sheet to a thickness of 200 μm,
Cut out three sheets of 20m x 30m, and then boil them using a double-tube extractor.
Extraction is carried out with hexane for 5 hours. After taking out the C6 insoluble matter and vacuum drying (7 hours under vacuum, 50° C.), the C6 insoluble matter is calculated using the following formula.

Measurement method of Tm by CDSC] Approximately 51
A sample of n9 was weighed, set in a total differential scanning calorimeter, heated to 170°C, held at that temperature for 15 minutes, and then cooled to 0°C at a cooling rate of 2.5°C/min. Next, in this state, the temperature is raised to 170"C at a heating rate of 10°C/min and measurements are taken. Among the peaks that appeared during the temperature rise from 0°C to 170°C, the apex position of the maximum peak The temperature is defined as Tm.

Melt flow rate (MFR) of ULDPE is not particularly limited, but is preferably 0.05 to 50L.
/10 minutes, more preferably 0.3~IO? /10
Use what you have.

Cofl is 0.05g-/10 minutes or less 0ULDPE? t-
If used, it becomes difficult to knead the filler, and if more than 50 fi'/10 minutes is used, film forming may become difficult.

The fillers used in the present invention include inorganic and organic fillers. Examples of inorganic fillers include carbonate (hereinafter referred to as "charcoal"), talc, limestone, clay, kaolin, alumina, aluminum hydroxide, magneur, magnenium hydroxide, carbonate sulfate, calcium sulfite,
Barium sulfate, aluminum silicate, Tfl-ironium,
Sodium silicate, potassium silicate, carbon tR magnenium,
Calcium oxide, titanium oxide, mica, glass flakes, zeolite, diatomaceous earth, perlite, vermiculite, shirasu balloons, glass microspheres, fly ash, glass peas, etc. can be obtained.

Examples of the organic filler include wood flour, pulp powder, and powder of phenolic resin and other synthetic resins.

Among these fillers, preferred are carbonaceous, Merck, phosphoric acid, barium sulfate, aluminum hydroxide, magnesium hydroxide, and the like. Further, two or more of these fillers may be used in combination.

The average particle size of the filler is 20μ or less, preferably 10μ
It is less than μ, more preferably less than 5 μ. If the particle size is large, the pore size of the resulting film will be large and the function as a porous membrane will be poor.

When a filler is added to a synthetic resin, the surface of the filler is often treated to improve dispersibility, and the method of the invention may also provide favorable results.

Surface treatment agents include fatty acids and their gold salts or acid amides, resin acids, titanate coupling agents, silane coupling agents, aluminate coupling agents,
Examples include wax and oil.

In the present invention, the blending ratio of ULDPE and filler is 10 to 80% by weight for the former and 20 to 90% by weight for the latter,
Preferably, the former has a weight ratio of 15 to 60, and the latter has a weight ratio of 40 to 9.
0 weight ratio, more preferably the former is 20 to 50 weight ratio,
The latter has a weight ratio of 50 to 80. If the ULDPE is 10% by weight, the film will be poorly formed, and if the filler is 90% by weight or more, that is, if the filler is less than 10% by weight, the film will have insufficient air permeability and moisture permeability. In terms of air permeability and moisture permeability, it is generally preferable to have a larger amount of filler. However, as the amount of filler increases, the strength of the film generally tends to decrease. Therefore, it is preferable to use a polymer that can be highly filled and has little decrease in film strength.
DPE is a polymer with superior properties compared to other polymers, which is why it is preferably used in the method of the present invention.

In addition to these two components, the present invention uses other thermoplastic resins (polyethylene, polypropylene, polystyrene, nylon, etc.), antioxidants, or heat stabilizers (hindered phenol, phosphite, etc.) as long as they do not impair the purpose of the present invention. system,
hydroquinone type, thionidel type, etc.), repair agents (benzophenone type, triazole type, salicylate type, hingoamine type, Ni complex type, etc.), dyes or pigments, flame retardants, antistatic agents, lubricants, mold release agents, plasticizers, Deodorizers etc. can be added. The above additives may be used in combination.

When melt-molding a film in the present invention, it is preferable to melt-knead the composition in advance. There are various ways to do this, but one example is open roll, Banbury mixer.
1 or melt-kneaded using a pressure kneader. However, these are generally batch operations and have poor productivity, so extrusion b'! The method used is preferred. As the extruder, a full-fract screw extruder may be used, but since the crosstalk may be insufficient, it is preferable to use an extruder with a kneading mechanism or a multi-screw extruder.

In the present invention, the pellets thus melt-kneaded are then melt-molded to produce a film. This step is carried out by a method commonly used for forming thermoplastic resin films. That is, the method is appropriately selected from the inflation molding method using a circular die, the T-die molding method using a T-die, and the like.

Next, the film (sheet) thus obtained is subjected to stretching treatment to produce the desired porous film. Stretching methods are generally broadly divided into uniaxial stretching methods and biaxial stretching methods, and both methods are possible in the present invention. - As the axial stretching method, a roll stretching method or the like is usually used. When using such a stretching method, it is preferable to suppress the necking phenomenon of the film as much as possible, and for this purpose, measures such as keeping the roll spacing as close as possible or suppressing shrinkage in the width direction of the film using pinch rolls or static electricity are taken. may be taken.

Biaxial stretching methods can be roughly divided into one-stage and two-stage methods.
The following method can also be used. There are various stretching methods such as a tenter set and a tubular set, but these can be used without particular limitation in the present invention.

Stretching is carried out at a temperature at least 10°C, preferably 20°C, more preferably 30°C or more lower than the Tm of the ULDPE.

Even if the difference between Tm and the stretching temperature is within 10°C, stretching can be performed well, but the resulting film will have poor porosity.

In other words, in terms of air permeability and moisture permeability, it is preferable that the stretching temperature is as low as possible. Generally, the stretching temperature of synthetic resins such as polyethylene is around its Tm, and if the stretching is too low, uneven stretching will occur. For this reason, the current method is to add a liquid compound as described above to improve the stretchability, but the method of the present invention allows stretching even at low temperatures as described above without adding a liquid compound. A major feature is that a highly desirable porous film can be obtained.

The stretching ratio is appropriately determined depending on the balance between mechanical properties, air permeability, and moisture permeability required for the film.

For applications requiring high air permeability, it is preferable to use a high stretching ratio of about 5 to 6 times. However, in this case, the tear strength of the film may be impaired, and in particular, if -axial stretching is carried out, a film that is prone to longitudinal tearing may be obtained. Therefore, it is generally preferable to carry out stretching at a low magnification of about 2 to 3 times. However, unlike the conventional method, which causes uneven stretching, the present invention allows stretching even at a low magnification of about 2 to 3 times. It is possible to obtain an excellent film.

The obtained film can be used as is, but
Annealing is also performed to suppress post-shrinkage.

The annealing temperature is preferably between the stretching temperature and the melting point of the ULDPE.

[Action and effect]

In the present invention, a porous film is obtained by converting the filler composition into a film and stretching the film, and its greatest feature lies in the use of the above-mentioned special ethylene copolymer (ULDPE). The effects obtained by this can be summarized as follows.

+> ULDPE itself is a synthetic resin with excellent flexibility, but even when a filler is added to it, it does not become very rigid, resulting in a film with a good feel.

ji) ULDPE has flexibility like an elastomer, but retains a certain degree of crystallinity, so a film with excellent strength, heat resistance, etc. can be obtained.

+++) ULDPE has a high ability to accept fillers and maintains flexibility and firmness even when filled with fillers as high as 70 to 80% by weight.

Therefore, this fully stretched film has a large number of holes and is breathable.
It has excellent moisture permeability.

+v) Films made of ULDPE and fillers have excellent stretchability. In particular, it can be stretched at low temperatures and low magnifications, making it an excellent porous film.
- A film is obtained.

(2) In carrying out the method of the present invention, inexpensive raw materials are used, existing equipment can be used for folding, and the productivity is high, making it possible to obtain economically advantageous porous films.

As mentioned above, the films obtained by this method, which have various characteristics, can be used in clothing items (golf wear, ski wear, raincoats, hats, etc.) and sanitary goods (disposable diapers, sanitary products, etc.).
! 4) Medical supplies (filters, band aids, etc.), industrial filtration media (for water treatment, air purification, various separators, etc.)
It has a wide range of uses.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples. The polymer and filler used in this example and the method for measuring the physical properties of the film are all shown below.

Film physical properties measurement method Strength at break: ASTM D882 Strength at break: ASTM D882 Tensile modulus: Tear strength: JIS P 8116 Moisture permeability: Fill a glass cup with a diameter of 85 mm with 50 M of pure water, place a test film on it, and Completely seal the bag and leave it in a room adjusted to a temperature of 23°C and a relative humidity of 50% for 10 days, and measure the weight loss to determine the moisture permeability. The results are shown in permeability per 1 m1 per day.

Polymer A used: ULDPE Butene-11,80,898
12172B // 0.8
0.907 122 89C〃 Propylene 1.1 0.897 121 69D L
LDPE Butene-11,00,921--Used filler a Calcium carbonate Nitto Funka Kogyo NCC-1010
1,2B Magnesium hydroxide Kyowa Chemical Industry Kismer 5B 1.0 Examples 1 to 9 A cross-wire extrusion pellet with the composition shown in Table 1 was prepared using a twin-screw extrusion ram. A film having a thickness of 60 to 85 μm was molded using an inflation molding machine using this pellet under the following conditions.

Die diameter: 100 m Molding temperature: 190°C Blow-up ratio: 1.7 Cross line height: 250 fin Next, this film was uniaxially rolled using a close roll rolling machine having a pinch mechanism to obtain a porous film. The stretching temperature, stretching ratio, and film thickness after stretching are shown in Table 1.

The physical properties of the film obtained here were measured in parallel to the stretching direction using the method described above. The results are shown in Table-1. The appearance of the film was evaluated based on the presence or absence of unevenness over time.

Comparative Examples 1 to 3 Cross-wire pellet dies,
Film molding and time delay treatment were performed. Here we get n
Table 2 shows the physical properties of the film. In addition, in Comparative Example 1, the time delay was so uneven that it was not possible to measure the physical properties.

Table 2 Patent applicant Japan Petrochemical Co., Ltd. Agent Patent attorney Takehiko Saito // Ryoji H Kawase
1 Procedural amendment February 6, 1988 Michibe Uga, Commissioner of the Patent Office 1 Display of the case 1985 Patent Application No. 290458 2 Name of the invention 3 Method of manufacturing porous film or sheet 3 Person making the amendment Related Patent applicant name: Nippon Petrochemical Co., Ltd. 4, agent name: Patent attorney (7175) Takehiko Saito 5. Details of the amendment in column 6 of the detailed description of the invention in the specification subject to the amendment (1) Specification (the same applies hereinafter) ) Correct "wo" to "to" on page 4, line 7.

(2) Delete r (cl J on page 5, line 8).

(Correct "fixing agent" on page 3117, line 14 to "weathering agent."

(Correct "Full Fluct" in line 9 of page 4118 to "Full Flight."

(5) In the first line of page 23, ``Ukiga'' is corrected to ``Ukikatsu''.

(6) “31
" is corrected to "31".

Claims (1)

[Claims] (1) Density is 0.860g/cm^3 or more, 0.910
g/cm^3, the boiling n-hexane insoluble content is 10% by weight or more, and the maximum peak temperature shown by differential scanning calorimetry (DSC) is 100°C or more.
10-80% by weight of olefin copolymer and 20% filler
A film or sheet obtained by melt-molding a composition comprising ~90% by weight is stretched at a temperature 10°C or more lower than the maximum peak temperature shown by DSC of the ethylene-α olefin copolymer. Process for manufacturing porous films or sheets.